/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param root TreeNode类 
 * @return int整型
 */
int sumOfLeftLeaves(struct TreeNode* root ) {
    if(root==NULL)
    {
        return 0;
    }

    int sum = 0;
    if(root->left && root->left->left == NULL && 
    root->left->right == NULL)
    {
        sum = root->left->val;
    }

    return sum + sumOfLeftLeaves(root->left) + 
    sumOfLeftLeaves(root->right);
}